Makefile.include: remove support for make <4
Makefile.include: remove support for make <4

RIOT-OS/RIOT,miri64/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,OlegHahm/RIOT,toonst/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,miri64/RIOT,kaspar030/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,basilfx/RIOT,authmillenon/RIOT,ant9000/RIOT,yogo1212/RIOT,authmillenon/RIOT,kYc0o/RIOT,toonst/RIOT,smlng/RIOT,jasonatran/RIOT,yogo1212/RIOT,basilfx/RIOT,yogo1212/RIOT,toonst/RIOT,smlng/RIOT,OlegHahm/RIOT,basilfx/RIOT,OTAkeys/RIOT,miri64/RIOT,OTAkeys/RIOT,ant9000/RIOT,ant9000/RIOT,kaspar030/RIOT,jasonatran/RIOT,ant9000/RIOT,yogo1212/RIOT,kYc0o/RIOT,smlng/RIOT,kYc0o/RIOT,authmillenon/RIOT,authmillenon/RIOT,basilfx/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,toonst/RIOT,toonst/RIOT,jasonatran/RIOT,kaspar030/RIOT,jasonatran/RIOT,basilfx/RIOT,miri64/RIOT,OTAkeys/RIOT,yogo1212/RIOT,OTAkeys/RIOT,smlng/RIOT,miri64/RIOT,smlng/RIOT,authmillenon/RIOT,kYc0o/RIOT,kaspar030/RIOT,OlegHahm/RIOT,OTAkeys/RIOT